Carl Sagan was one of my heroes when I was growing up. His hit TV show ‘Cosmos’ was truly inspiring. Probably one of the reasons why I was drawn to science in the first place. My copy of his eponymous book was a school prize, still on my shelves. He came up with some great ideas, many of which were highly imaginative and, let’s be honest, pretty speculative. It was part of his broader appeal to push the boundaries of possibility, particularly regarding the potential for extraterrestrial life.

Later in his life, he seemed to become more conservative, more sceptical, more apprehensive about the darkness of superstition. These are natural changes as people age, of course. I assumed that Sagan had lost that early zest, but I was wrong. Having read this revisionist book, I realise now I was wrong about several things.

I always knew that Sagan had collaborated with the Russian scientist I. S. Shlovskii on a book entitled “Intelligent Life in the Universe” back in 1966, but I was unaware of the so-called Stanford Paper, which is the central plank of Zygutis’s book.

The full title of Sagan’s 1962 Stanford Paper is “Direct Contact Among Galactic Civilizations by Relativistic Interstellar Spaceflight”. It pre-dated Erich von Däniken, and beat Zecharia Sitchin’s 1976 book “The Twelfth Planet” by a country mile. How could that possibly be important, given the way Sagan seemed to vilify pseudo-scientists later in his life? Read on…